Different concentrations of mitomycin C for haze prevention in photorefractive keratectomy

Abstract

Objective: Evaluate the usefulness of two concentrations of mitomycin C for haze prevention in photorefractive keratectomy.

Methods: An experimental randomized study was conducted of 26 eyes of 17 patients with myopic defects. The patients were divided into two groups according to their mitomycin C doses (Group 1: 0.02% and Group 2: 0.002%). The main response variable was the presence of haze. Verification was performed of the correlation between haze magnitude and the degree of the ametropia treated, ablation depth, endothelial microscopy, and visual and refractive results.

Results: At six months most patients in Group 1 did not have any haze (eight eyes / 57%), whereas 0.5 (6 eyes / 50%) in Group 2 still had haze. In severe ametropia, haze was larger in Group 2 than in Group 1 throughout the postoperative period, the greatest difference being observed in the sixth month with 0.5 ± 0.4 vs 1.5 ± 0.32. In ablations > 75 microns, Group 2 ended with more haze than Group 1, with 0.5 ± 0.44 vs 1.75 ± 0.76. Uncorrected visual acuity was more affected in Group 2. No endothelial damage occurred in either group.

Conclusion: The presence of haze prevails in cases treated with 0.002% doses of mitomycin C, as compared with 0.02% doses, though in this case both groups maintained an appropriate visual and refractive result and low endothelial toxicity.

Key words: Photorefractive keratectomy; corneal haze; 0.02% and 0.002% mitomycin C; endothelial damage.